Conventional tablet coating and polishing apparatus which have been in use for a number of years generally comprise a large drum or pan that is mounted on a rotatable axis. Tablets for pharmaceutical purposes as well as other uses are placed into the pan and upon rotation of the pan a coating material is applied. The pan rotates at a relatively slow speed such as 20- 25 RPM. After a sufficient number of coatings have been applied to the tablets they are ready for removal from the pan. In small coating apparatus, removal of the tablets can be made by hand. However, when production is on a large scale and pans of approximately 48 inch diameter are used it is apparent that the removal of about nine cubic feet of tablets becomes burdensome if done by hand. Thus, apparatus have been designed for inserting into conventional coating pans which will cause the tablets to be removed automatically by gravity feed.
U.S. Pat. No. 2,807,230, C. H. Brammar, issued in 1957, relates to an unloading device that may be removably coupled to a coating pan. The structure in that pan was designed for a coating pan having a horizontal axis. In particular, it utilizes a chute having an inlet which will scoop up a quantity of tablets from the bed of the tablets as the pan rotates. When the chute rotates from a lower position where it has scooped up tablets to a higher position the tablets begin to flow through the chute by gravity and will eventually flow to an outlet of the chute which is positioned on the exterior of the pan through its opening. It is apparent that in order for the tablets to flow through the unloader chute by gravity that the chute must be positioned at an angle to the horizontal axis of the pan. In the Brammar structure this angle can be approximately 30.degree. - 40.degree..
In more recent years the popularity of tablet coating pans on an inclined axis has grown significantly. Attempts to apply unloading chutes of the type taught in the Brammar patent to coating pans having an inclined axis of rotation have not led to satisfactory results. As taught in the Brammar patent it is necessary for the unloading chute to be at an angle to the axis of rotation of the coating pan which is greater than the angle between the horizontal and the axis of rotation of the coating pan in order that gravitational flow can occur. Therefore, as the axis of the pan is raised on an incline the maximum of available discharge angle for the unloader chute decreases. Consequently, the travel speed of tablets exiting through the chute will decrease. This in turn will require the pan to rotate at a much slower speed in order for a Brammar unloader to completely discharge all of the tablets collected during each rotation. Depending on the angle of the pan axis and its rotational speed it is quite possible that there will be recirculation of tablets within the unloader chute. This inability to completely discharge all of the tablets collected during each rotation will cause damage to the tablets in many instances since they are colliding with each other at a fairly substantial force.